Drinking tea and nibbling on dark chocolate could boost your heart health. (Image: Getty)
Nibbling on dark chocolate, sipping a cuppa may sound like heaven, but it can lower your blood pressure too, scientists have discovered. UK scientists have been investigating the role of naturally occurring plant compounds called flavan-3-ols to see if they can help lower blood pressure and improve blood vessel function.
A new study from the University of Surrey has found that flavan-3-ols—found in cocoa, tea, apples, and grapes—have miraculous heart and blood pressure health-boosting effects. According to University of Surrey researchers, they “show promise in improving blood pressure and vascular function, but are currently not used for cardiovascular prevention.”
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Apples and grapes are also high in flavan-3-ols. (Image: Getty)
Their study, published in the European Journal of Preventive Cardiology, analysed data from 145 randomised controlled studies involving 5,200 participants.
It found that regularly eating flavan-3-ols can reduce blood pressure readings, particularly in people with elevated or high blood pressure.
In some cases, the average blood pressure-lowering effects were comparable to those seen with some medications.
Flavan-3-ols were also found to improve the function of the endothelium – the inner lining of blood vessels – which releases substances that aid blood flow and is crucial for overall cardiovascular health.
Damage to your endothelium can put you at risk of a range of health problems, like atherosclerosis, when plaques narrow the arteries, as well as related conditions like heart attacks and stroke.
Researchers said the improvement to endothelial function happened separately to changes in blood pressure.
This suggests a broader positive impact on the circulatory system, they wrote, adding that their findings support the use of flavan-3-ols for prevention of cardiovascular issues.
Professor Christian Heiss, lead-author of the study and Professor of Cardiovascular Medicine at the University of Surrey, said: “The findings are encouraging for those looking for accessible ways to manage their blood pressure and support their heart health through enjoyable dietary changes.”
But this does not mean you can gorge on choccy treats – the small amounts are key, as is choosing dark over milk.
Nor can flavan-3-ols replace medications if you need them to bring down your blood pressure – but they can serve as a useful addition to your “healthy lifestyle”, Prof Heiss went on.
“Incorporating small amounts of commonly consumed foods like tea, apples, dark chocolate, or cocoa powder into a daily balanced diet could provide beneficial amounts of flavan-3-ols,” he explained.
“While not a replacement for prescribed medications or medical advice, including more flavan-3-ol-rich foods in a daily routine could be a valuable addition to a healthy lifestyle, especially for those with higher blood pressure.
“These are findings that, although promising, require ongoing investigation.”
In 2022, the Cosmos trial (Cocoa Supplement and Multivitamin Outcomes Study), which followed over 21,000 people, found that cocoa flavanols, but not multivitamin supplements, reduced deaths from cardiovascular disease by 27%.
Writing in The Conversation about their findings, Professor Heiss explained how the 145 studies tested a range of flavan-3-ol-rich foods and supplements, including cocoa, tea, grapes, apples.
They also isolated compounds like epicatechin and measured their effects on two key cardiovascular markers: blood pressure and flow-mediated dilation (FMD), a measure of how well the inner lining of blood vessels functions.
The studies ranged from short-term (a single dose) to longer-term interventions lasting weeks or months.
On average, participants consumed about 586 mg of flavan-3-ols daily; roughly the amount found in two to three cups of tea, one to two servings of dark chocolate, two tablespoons of cocoa powder, or a couple of apples.
Regular consumption of flavan-3-ols led to an average drop in office blood pressure of 2.8 mmHg systolic (the top number) and 2.0 mmHg diastolic (the bottom number).
But for people who started with elevated blood pressure or diagnosed hypertension, the benefits were even greater with reductions of up to 6–7 mmHg systolic and 4 mmHg diastolic (the bottom blood pressure number).
Professor Heiss explained: “Flavan-3-ols show up in some of our most familiar foods: cocoa, green and black tea, grapes, apples and even some berries.
“That slightly tart or bitter note you taste in dark chocolate or strong tea? That’s flavan-3-ols at work. Scientists have long been interested in their health effects.
“Regular consumption of flavan-3-ols led to an average drop in office blood pressure. But for people who started with elevated blood pressure or diagnosed hypertension, the benefits were even greater, comparable to the effects of some prescription blood pressure medications and could significantly lower the risk of heart attacks and strokes.
“We also found that flavan-3-ols improved endothelial function, with an average 1.7% increase in FMD after sustained intake.
“This benefit appeared even in participants whose blood pressure was already normal, suggesting these compounds may help protect blood vessels through multiple pathways.
“Side effects were uncommon and typically mild, usually limited to minor digestive issues, suggesting that adding flavan-3-ol-rich foods to your diet is generally safe.”
Supporting cardiovascular health
Professor Heiss added: “While the benefits were most pronounced in those with high blood pressure, even people with normal readings saw improvements in vascular function. This suggests flavan-3-ols may help prevent cardiovascular problems before they begin.
“High blood pressure is one of the major drivers of heart disease worldwide, even at levels that don’t qualify as full-blown hypertension (140/90 mmHg or higher).
“Recent guidelines from the European Society of Cardiology now recognise that even ‘elevated’ blood pressure (120–139 systolic and 70–89 diastolic) carries increased risk.
“Lifestyle changes, particularly diet and exercise, are recommended by doctors as first-line strategies. But patients and even healthcare providers often lack clear, specific guidance on which foods truly make a difference.
“Our findings help fill this gap by showing that boosting flavan-3-ol intake through everyday foods may offer a simple, evidence-based way to support cardiovascular health.”
How much flavan-3-ols should we have?
He added: “The studies we reviewed suggest that 500–600 mg of flavan-3-ols daily may be enough to see benefits.
“You could reach this by combining two to three cups of green or black tea, one to two servings (about 56g) of dark chocolate or two to three tablespoons of cocoa powder, two to three apples, plus other flavan-3-ol-rich fruits like grapes, pears and berries
“Small daily swaps, then, like trading a sugary snack for an apple and a piece of dark chocolate or adding an extra cup of tea, could gradually improve your heart health over time.
“Because flavan-3-ol content can vary between foods, monitoring your blood pressure at home may help you see if it’s making a difference for you.
“More research is needed, particularly in people with diabetes, where the results were less consistent. We also need to better understand how flavan-3-ols interact with medications and whether even greater benefits can be achieved when combined with other healthy habits.
“But the evidence is now strong enough to recommend flavan-3-ol-rich foods as part of a heart-healthy diet. As clinicians seek practical, affordable lifestyle strategies for patients, these findings bring us closer to the idea of using food as medicine.
“Of course, flavan-3-ols aren’t a magic fix. They won’t replace medication for everyone. But combined with other healthy habits, they may offer a meaningful – and delicious – boost to cardiovascular health.
“And unlike many health fads, this isn’t about exotic superfoods or expensive powders. It’s about foods many of us already enjoy, used a little more intentionally.”